Ask Jacksons: How do you rescue dull patches in an oil painting?

Dull patches in an oil painting are caused by a number of different factors. An absorbent painting surface (such as an absorbent acrylic gesso) can cause the paint to sink into the ground, making it appear dull. Too much solvent being used to thin the oil paint can make it more likely to sink. Additionally certain colours, such as Raw or Burnt Umber, are more prone to appearing matte and dull due to their high pigment to binder ratio.

Retouching varnish can be applied to a touch-dry oil painting to protect it while it is curing. As well as providing protection, a retouching varnish also helps revive dull spots in a painting, providing an even finish.  

It is best to prevent sinking occurring in the first place. Acrylic-based gesso primers, which are used to prepare most ready-made canvases, are absorbent and can ‘draw in’ oil from the paint film. An oil primer can be applied on top of acrylic-primed canvas to reduce its absorbency. If the issue is that the paints you use have a high pigment to binder ratio, you can add an oil medium to your paints to help maintain sheen and body. To find out more about oil painting mediums, visit our blog post on the subject.

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